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COPYRIGHT DEPOSm 



HOW TO 
READ A DRAWING 



BY 

VINCENT C. GETTY 



WITH 62 ILLUSTRATIONS 




PHILADELPHIA & LONDON 
J. B. LIPPINCOTT COMPANY 

1912 



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COPYRIGHT, I912, BY J, B. LIPPINCOTT COMPANY 



PRINTED BY J. B. LIPPINCOTT COMPANY 

AT TJIE WASHINGTON SQUARE PRESS 

PHILADELPHIA, U. S. A. 



©CI.A327924 



PREFACE 



The understanding of a drawing has appeared to many 
who are not familiar with this branch of education to be a 
very difficult study. It has been the writer's province to 
know that there are a vast number of mechanics who look upon 
drawings with awe, thinking that to become proficient in the 
understanding of drawings they first must have scholarly or 
technical knowledge. It is the purpose of this book to show 
that this is a very erroneous idea, it being a fact that this 
branch of education requires less study than almost any other 
branch of useful knowledge; and all the education necessary 
is, that the student be able to read and understand the English 
language. 

As to its usefulness, I doubt if there is any branch of 
education that compares with it; for by drawings we can 
express our thoughts and desires more clearly and concisely, 
and they can be understood more readily, than by any other 
system known to the civilized world. In the commercial or 
industrial world no work of consequence is carried on without 
them, and, from the making of a special bolt to the building 
of a railroad, drawings are necessary. 

Who then, realizing this, can afford to be without this 
knowledge? Surely not those whose wages are small, for 
their wages will always be small unless they acquire useful 
knowledge which will tend to better their conditions in life; 
surely not those in the higher stations of life, for unless they 
understand drawings they must depend solely upon some one 
else who has this knowledge, in order that their desires may 
be carried out. The manager, purchasing agent, superintend- 
ent, foreman, mechanic, clerk, shopman, or laborer, will 
find this knowledge to be a stepping-stone toward success. 

In this book it has been my endeavor to explain the reading 
of a drawing without the use of technical terms; but where 

3 



4 PREFACE 

it has been absolutely necessary to use such terms, their mean- 
ing has been fully explained. 

I also wish the student to understand that, while I have 
divided the different classes of drawings under different 
headings, this work should be studied as a whole; as failure 
to understand thoroughly any part of it may result in a mis- 
understanding of it all. 

The main principles of drawing have been thoroughly 
explained and sufficient examples given to enable any one 
to understand clearly any drawing; but I want to impress 
upon the student that, in order to master it, he must study it 
carefully and conscientiously, for, in the words of a great 
philosopher, ''Nothing great is accomplished without an 
effort." 

In conclusion, I want to add that, while this book was 
written with the intention of helping many, if it helps a few 
I shall be repaid. 



CONTENTS 



CHAPTER PAGE 

I. Method of Representing Objects 7 

II. Lines Used in Projection Drawing 12 

III. Views Needed 15 

IV. Universally Used Structural Shapes 17 

V. Scales Used in Drawing 22 

VI. Bolts, Nuts, Rivets, etc 25 

VII. Structural Details 31 

VIII. Mechanical Drawings 43 

IX. Gearing; Finishing; Storage Tank ; and Valve 47 

X. Architectural Drawing _ 54 



HOW TO READ A DRAWING 



CHAPTER I 

Method of Representing Objects 

It is my intention to explain in this work the method by 
which an object may be described by a drawing. 

The branch of drawing about to be explained is known as 
Projection Drawing, as projection drawing not only enables 
those who are familiar with it to know exactly what the object 
represented looks like, but also shows the object in such a 
manner that the surface 
or any line or angle of 
the object can be read- 
ily measured on the 
drawing. 

There is, however, 
another branch of draw- 
ing, called Perspective 
Drawing, that is very 
useful in showing what 
an object looks like, 
but would be of very 
little use to those who 
wish to construct the 
object so represented. 
Even those who are thoroughly familiar with perspective draw- 
ing would have great difficulty in measuring or determining the 
size of the object represented, for, while they might know posi- 
tively that the two ends were of the same size or that the tops 
or bottoms were the same, yet, if they were to measure on the 
drawing either of the two ends, or the top or bottom of the 
object, they would find that they are there shown to be of 
different dimensions. 

7 




Perspective view. 



8 HOW TO READ A DRAWING 

This is clearly shown in Fig. i , it being a perspective draw- 
ing of a rectangular object, similar in shape to an ordinary brick. 

This figure represents the rectangular shape as it actually 
appears to the eye when looked at from a certain position. 
In this drawing three sides of the object are shown and the 
other three sides are hidden, but in projection drawing only 
one side is usually shown, the other sides being hidden. 

HOW OBJECTS ARE SHOWN BY PROJECTION DRAWING 

Suppose we were to place a brick or some other rectangular 
object, with one of its largest sides down, upon the top of a 
table, or the floor of a room, or any other flat surface; then, 
if we were to stand so that we could look down upon it with 
the eye directly above it, the outline of the top of the object 
would appear to the eye as it is represented in Fig. 2. As we 
were then looking at the top of the object, this view would 

be known as the top view, or 
Fig. 2. PLAN view, as it is sometimes 

called. 

Rule. — A drawing which 
represents an object as if it 
were resting upon the top of a 
table the floor of a room, or any 
other flat surface, the observer 
looking directly down upon it 
from above, is called a top view or plan view. 

If we were to look directly at the side (long side) of the 
object, with the eye at the sam.e level as the top of the table 
upon which the object is resting, the outline of the side of the 
object would appear to the eye as it is represented in Fig. 3 . 
As we were then looking at the side of the object, this view 
would be known as the side view, or front view, or, as it 
is sometimes called, side elevation. 

Rule. — ^A drawing which represents an object when ob- - 
served directly from the side, with the line of vision upon the 
same level as the top of the table upon which the object is 
resting, is called the side view or side elevation. 

Let us now turn the object around so that its small side, 






METHOD OF REPRESENTING OBJECTS 9 

or end, can be viewed from the same position that the large 
side was viewed from; then, viewing this small side or end in 
the same manner in which we viewed the large side, it will 
appear to the eye as it is represented in Fig. 4. As we were 
then looking at the end of the object, this view would be 
known as the end view or end elevation. 



Fig. 3. 



Fig. 4. 






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Rule. — ^A drawing which represents an object when ob- 
served directly from its end, with the line of vision upon the 
same level as the top of the table upon which the object is 
resting, is called an end view or end elevation. 

The manner in which the top, side, or end of an object 
is shown has now been explained, but there is another 
view to be shown, namely the 
bottom view. ^^^- 5» 

Let us now imagine that 
our object has been turned 
over so that it rests upon one 
of its sides; the bottom view 
would now be visible ; then, by 
viewing it in the same manner 
in which the side was viewed, 

the bottom view would appear to the eye as it is represented 
in Fig. 5. As we w^ere then looking at the bottom of the 
object, this view would be known as the bottom view. 

It may be well to state here that sometimes the end or 
the side view of an object could be considered the front or 
the rear of an object ; when this occurs, the view shown would 
be known as front view or front elevation, or rear 
VIEW or rear elevation. 

In Fig. 6 the different views are placed in their proper 
positions — that is, top view at the top of the drawing, end 
views at each end of front view, side view or front view in the 



10 



HOW TO READ A DRAWING 



centre, bottom view at the bottom, and view of rear side at 
the extreme right-hand side of the drawing. 

For convenience, I have repeated Fig. i on this page, it 
being a perspective drawing of Fig. 6; also the corners of the 
object are marked with letters of the alphabet; these letters 
correspond with the letters in Fig. 6. This was done in order 
that the different drawings may be readily compared. 

In Fig. 6 the letters A, B, C, D represent the Top View 
or Plan View of the object shown in Fig. i ; D, C, H, G repre- 




Different views. 



sent the Side View or vSide Elevation, or, as it is sometimes 
called, the Front View or Front Elevation; A, D, E, H and 
C, B, G, F represent the ends of the object, which would be 
known as the End View or End Elevation; H, G, E, F repre- 
sent the bottom view, and A, B, E, F represent the Rear 
View or Rear Elevation of the object. 

As there are six sides to our object, it will be noticed that 
in Fig. 6 all the six views are shown ; all of these views are not 
absolutely necessary in this case, as the object represented 
is very simple in construction; but all the views are shown in 



METHOD OF REPRESENTING OBJECTS 



11 



order that the student may see the manner in which all the 
surface views of any objects may be represented by projection 
drawing. In order that the student shall clearly understand 
why these different views are shown in this manner, I give 
another illustration in Fig. 7. 

Fig. 7 shows the different views seen in Fig. 6, joined together. 
In order that this illustration may be thoroughly understood, I 
wish to have the student cut out of cardboard a figure similar 
to the one shown by the heavy lines of Fig. 7, then, by bending 
the cardboard where the lines are dotted, the cardboard will form 
the figure of a rectangular object similar to the one shown in 
Fig. I . This then will give the student a practical example of 
why the views are shown by the method used in Fig. 6. 



Fig. 7. 









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Cardboard diagram. 

To be able to understand how to read a drawing, the whole 
secret lies in being able to see in the mind what the object rep- 
resented looks like ; for in projection drawing the object is not 
represented as it is shown by a photograph, for in a projection 
drawing you see only one view at a time, and the student must 
remember that the view shown represents the outline, or profile, 
of the object ; and every line that represents the form or shape 
of the object is shown exactly as it would appear to the eye if 
the eye was at a point directly facing the object. 

Therefore, study carefully every word of this chapter, for 
if the student clearly understands all that is contained in it 
he will have mastered the fundamental principles of how 
drawings are read and the balance of this study will be found 
to be very simple. 



CHAPTER II 

Lines used in Projection Drawing 

There are several kinds of lines used in projection drawing, 
the ones commonly used are as follows : 

The full line 

The dotted line 

The dash and dotted line 

The Hght full line . 

The full line is most employed, it being used to draw the 
outline and all parts of an object which can be seen with the eye. 

The dotted line consists of a series of very short dashes, and 
is used to show that part of an object that is not visible to the 
eye; for instance, in Chapter I, page lo. Fig. i, the edge or out- 
line of the object marked by the letters B and F, E and F, and 
F and G cannot be seen by the eye ; thus these edges are shown 
by the dotted lines. This rule of showing invisible parts of the 
object by a dotted line is always used in projection drawing. 

The dash and dotted line is used to indicate centre lines 
of an object, or to show from what points a section has been 
taken. The use of this line will be fully explained later. 

The light full line is used for showing dimensions on a 
drawing (that is, the distance from one point to another) ; 

sometimes, however, the dash and dotted line ( — ) 

is used for this purpsoe, as it serves to prevent the dimension 
lines from being mistaken for the full line which is used to 
show the outlines of the object, but, as a general rule, most 
dimensions are shown by the light full line. The student will 
soon learn to distinguish the different lines, so that no mistakes 
or confusion will result. Any other lines not shown here will 
be fully explained when the necessity for using them arises. 

In Chapter I (page lo) it has been stated that all the views 
shown were not absolutely necessary, as the object was very 
simple in construction, and they were given merely to show 
to the student the proper location of the different views by 
which difficult objects may be represented. In this chapter 
it will be explained why all these views were not necessary. 

12 



LINES USED IN PROJECTION DRAWING 



In Fig. 8 this same object is shown by only three views, — 
namely, top view, end view, and side view. In this figure 
dimensions and dimension lines are shown, which will help 
to explain why these three views are sufficient to show the 
object properly. At each end of all the dimension lines is 

placed an arrow point ( >) . This symbol is employed to show 

from what points the dimensions are taken; the dimension 
lines are light full lines about one-half the thickness of the 
outlines of the object. 

In this drawing it will be noticed that two small marks ('') 
are placed after the figures. These two marks are used to 
denote inches ; when only one 
is used (') it denotes feet; 
thus I '-2'' is read one foot 
and two inches; ic'-3>^" is 
read ten feet and three and 
one-half inches. This method 
is universally used to repre- 
sent feet and inches on all 
drawings; thus, the top view 
of Fig. 8 shows the object to 
be nine inches long by four 

and one-half inches wide, the side or front view shows the object 
to be of the same length and two and one-half inches deep, the 
end view also shows the same dimension for the width that is 
shown in the top view. While this latter dimension is not 
absolutely necessary, it helps the student to see at a glance that 
it is an end view, as the dimension showing the width of the 
top is the same dimension as the width in the end view. 

It will be seen now that these three views are all that is 
necessary to properly show the construction of the object, as 
the top view shows the length and width, the side or front 
view the depth, and the end view the shape of the ends. As 
these views show the object complete, no others are necessary, 
for when the top of an object is shown the bottom is always 
understood to be the same unless some other view shows that 
the bottom is different ; also when one side or end of an object 



Fig 


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14 



HOW TO READ A DRAWING 













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is shown the other side or end is regarded as the same unless 
some other views show that they are different. This perhaps 
can be more clearly understood by referring to Fig. 9. 

Fig. 9 shows an object similar to the one pictured in Fig. 8, 

except that the bottom 

^^^- 9- corner of the front of the 

object has been cut off. 
This cut-off is shown by 
the top view and front 
view to extend the entire 
length of the object. 
The top view and side 
view show that the cut 
begins i>^" back from 
the front and Y^" up 
from the bottom; in 
the top view the exact 
point where this cut starts, not being visible to the eye, is 
shown by a dotted line. In the front view the point 
where the cut starts being visible, it appears as a full line. 
The end view shows the shape of the object very clearly. 

This brings me to the 
point where I desire emphat- 
ically to impress upon the 
student the necessity of 
looking at all the views of 
the object that are shown 
before determining w^hat the 
object really looks like. For 
example, in Fig. 10 the top 
view and side or front view 
are the same as the top and 

side views of Fig. 8. The end view, however, shows that the 
shape of the object is different, it having a wedge-shape instead 
of the rectangular shape shown in Fig. 8. Thus it will be seen 
that all views of the object must be taken into consideration 
before determining what the object represented really looks like. 





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CHAPTER III 



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Fig. II. 



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Views Needed 

In all practical projection drawings only those views are 
shown which will actually describe the object; for instance, 
in Fig. II is represented a cylinder. The lines marked A B 
and C D are known as centre lines. In this drawing only two 
views are necessary to describe the object properly. The 
upper view shows that the top of the object is circular in shape, 
and the dimension 2" shows the diameter. Now, if we know 
that the top is circular and that the object 
is a solid body, all that remains for us to 
know is the depth, for every solid circular 
body must have a depth. By looking at the 
lower view, which is projected from the cen- 
tre lines A B, we see that the object is 6" 
deep. Thus the views which are shown are 
stifhcient to describe this object properly. 

There is one other view which we must 
take into consideration, and that is called 
the Sectional View, or section of an object. 
This view is often of great help in determin- 
ing exactly what an object looks like at a 
point where it can not be shown prominently 
by either top, bottom, side, or end views. 

Fig. 12 represents an object similar in 
shape to a spool. The top view shows that O 

the object at its ends, or at the top and 
bottom, is circular, the outer circle denoting the extreme 
diameter; the intermediate circle is that portion which is 
not visible to the eye when looking down upon it from above, 
and the inner circle denotes the size of the hole which runs 
through the object. The elevation, or front view, shows the 
outlines of the object as they appear when looking at the object 
as though it were resting on one of its fiat ends. The dotted 



10 



16 



HOW TO READ A DRAWING 



lines indicate the hole which runs through the object, but 
which is not visible to the eye. 

Fig. 13 represents the same object as above described, but 
instead of a side view or side elevation a section has been taken 
through the centre line A B, — that is, the spool is imagined 
to be cut in half lengthwise, and that part which is toward 
the front removed; then it is looked at in the same manner 
as if it were a front view or front elevation, but in order to 



Fig. 12. 



Fig. 13. 




distinguish it from any of these views the section lines are 
employed. These lines are simply light lines drawn at an 
angle inside of all the outlines. 

The student should by this time be familiar with the method 
by which simple objects are shown by projection drawings, 
and also with the main principles b}^ which any object may be 
shown. However, there are many other minor points which 
shall be fully described as we proceed. 



CHAPTER IV 



The 
Fig. 14. 



fJ.A 



Universally Used Structural Shapes 

following chapter is designed with the purpose of 
briefly showing and describing the various struc- 
tural shapes which are universally used in the 
construction of buildings, bridges, etc. 

Fig. 14 represents the top, end, and front views 
of what is known as an I Beam. This shape de- 
rives its name from the fact that the end view 
resembles the ca})ital letter I. 

The end view of Fig. 14 shows the shape of the 
I beam, the front view represents the depth and 
length of the beam, and the top view shows the length 
of the beam and the width of the flange. In the end 
view the top and bottom portions of the figure are 
known as the flanges, and that portion between the 
top and bottom flanges is known as the web. As will 
be seen, the front view or length is represented by 
two upper and two lower lines, being projected from 
the sharp corners of theflangeshownin the end view. 

I beams are rolled to various sizes and weights; 
these sizes and weights are given in hand-books 
which are published by manufacturers of this ma- 
terial. I beams are generally known by the depth 
of the beam and weight per foot. 



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18 



HOW TO READ A DRAWING 



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§ 



Fig. 14 represents a 12" I beam weighing 31}^ pounds per 
foot ; this is generally written 1 2 " I 3 1)^ lbs. The outlines of the 
top view indicate the top flange, and the two dotted lines 
represent the web. The method of projecting the top view 
or flange from the end view is illustrated in Fig. 14, it being 
shown in a perpendicular position, but, as this method of 
indicating the top view takes up considerable space on a draw- 
ing, the form generally used is that seen in Fig. 15. Here, 

Fig. 15. 



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the top view is drawn immediately above the front view in a 
horizontal position, instead of a perpendicular position as is 
shown in Fig. 14. 

Fig. 16 represents what is known as a channel. This 
shape or section is similar to the I beam, except the flanges, 
which do not extend over the web on one side. This shape is 
also rolled to various weights and sizes; the size shown in 
Fig. 16 is 10" deep and weighs 15 pounds to each foot; this is 
generally written 10" C 15 lbs. The end view of Fig. 16 
shows the shape of this section. 

The front view is projected from the end view in the same 
manner as is shown in Figs. 14 and 15. 

The top view represents the top flange. The first line 
directly above the front view vshows the outer edge of the 



UNIVERSALLY USED STRUCTURAL SHAPES 19 

flange, the dotted line indicates the face of the web, and the 
next full line represents the back of the channel. 

Fig. 17 represents an angle. This shape or section is also 
rolled to various sizes and weights. It is, however, generally 
known by the size of its legs, — i.e., the distance from the corner 

Fig. 16. 



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or back of the angle to the extreme edge of the leg, and the 
thickness of the metal of which the angle is composed. 

Fig. 17 shows a 3" x 3" x %" angle, which is generally writ- 
ten 3" X 3" X %" L. The top view is above the front view, and 
is represented in the same manner as the top view of the 



Fig. 17. 



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channel shown in Fig. 16, but we distinguish it from a channel 
by the end view, which clearly shows the shape of the angle. 
In this illustration we have a practical example of why all 
the views shown must be taken into consideration before we 
know positively what the object represented really is. 



20 



HOW TO READ A DRAWING 



Fig. 1 8 represents a T bar or T shape. This shape is known 
by the size of the legs and the weight per Hneal foot. Fig. i8 
shows a 4" X 4" X 13.7 lbs. T. As the thickness of the metal 
varies in the legs of the T, the weight per foot is given. This 
shape gets its name from the fact that the end view resembles 
the capital letter T. 

The top view is projected from the end view by the same 
method as that used in showing the projection of the I beam, 
as illustrated in Fig. 14, but for convenience, as explained 
before and as is shown in Fig. 15, this view is placed directly 
above the front view. This brings me to the point where I 
must explain that the different views of an object may be 



Fig. 18. 



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placed in any position to suit the convenience of the drafts- 
man, but those which are not in their regular position (see 
Fig. 6) should be so marked as to show which view they 
represent. However, a view is sometimes placed out of its 
regular position without being so marked where it is apparent 
for various reasons that it could not be taken for any view 
other than the one intended. 

Fig. 19 represents what is known as a Z bar, which derives 
its name from the fact that the end view resembles the capital 
letter Z. This section or shape is generally known by the depth 
(4"). width of the flange (sKe'O' and thickness of metal (Kb'O- 
This is generally written 4" x ^y^i' x Ke" Z bar. The sizes and 
weights of all Z bars are shown in detail in any of the hand- 
books published by the manufacturers of this product. 



UNIVERSALLY USED STRUCTURAL SHAPES 21 

The views are shown by the same method used in the other 
illustrations. While the above illustrations by no means 
cover all the different shapes manufactured or used in the 
construction of buildings, bridges, etc., yet I have shown the 



Fig. 19. 











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main shapes that are used for general construction purposes, 
and in the following chapters will be shown some of the methods 
by which these shapes may be assembled to form the various 
members used in construction work. 



CHAPTER V 

Scales used in Drawing 

In making drawings and likewise in the understanding of 
drawings, there is a factor which we must take into consider- 
ation, and that is what is known as a scale. A scale is an 
instrument which is used to measure distances on drawings. 

The student of course knows that it is impossible to make 
drawings of the full size of very large objects; so where it is 
desired to make a drawing smaller than the object, a scale is 
used to measure distances instead of the standard ruler. 
For example, a drawing one-fourth of the natural size of an 
object one foot long would be made only 3" long, because 3" 
are one-fourth of one foot; therefore, on the drawing 3'' would 
be equal to one foot or 12'^ This is known in drawings as a 
scale of 3" to the foot, or, in other words, a scale which is made 
or graduated to 3'' to the foot is simply a ruler by which 3" 
are equal to 12'' of the standard rule. 

A drawing, however, may be made to any scale desired: 
for instance, if it were made one-fourth size, it would be known 
to be to the scale of 3" to the foot; if made one-eighth size, 
it would be known as iK" to the foot. 

K2 size would be equal to i" to the foot. 
Ke size would be equal to K" to the foot. 
]4i size would be equal to %" to the foot. 
K2 size would be equal to %" to the foot. 
jis size would be equal to %" to the foot. 

When a drawing is well made, the scale to which it is 
drawn is usually marked under the title of the drawing, and 
is generally written in the following manner: 3''=i'-o" or 
i"=i'-o", etc. 

Scales are usually made 6 inches and 12 inches long, and 
in shape are either triangular or flat. A scale 6 inches long 
is shown slightly reduced in Fig. 20. One edge is divided or 
graduated the same as the standard ruler, — that is, into inches, 



SCALES USED IN DRAWINGS 



23 



Fig. 20. 




i<^ 



half inches, quarter inches, eighths of an inch, and sixteenths 
of an inch. This scale is used in the same manner as the ordi- 
nary ruler, or for making full-sized 
drawings. 

The other edge contains two 
scales, — namely, i" to the foot and 
Vi to the foot. These sizes are indi- 
cated at the ends of the scale in large 
figures. In the inch scale, starting 
from the left end of the scale and 
reading toward the right, this being 
the scale of i" to the foot, each inch 
is equal to one foot or 12 standard 
inches. 

The first (standard) inch is di- 
vided first into four equal parts, each 
of which represents one-fourth foot 
or three inches; for convenience in 
reading the scale, these divisions are 
marked with the figures 3,6, and 9 
and represent respectively that num- 
ber of inches. By this then we see 
that we can measure in inches any 
part of a foot. Each of these inches 
is divided into four parts, each part 
representing one-fourth of one inch, 
and, if so desired, each one-fourth 
inch may be again divided to repre- 
sent one-eighth of an inch. Thus it 
will be seen that with a scale which 
is so graduated that \" is equal to 
12", or I 'o" , we are able to measure 
inches or any part of an inch down 
to one-eighth of an inch. 

Now, starting at, and on the same 
line as zero (o), each inch reading toward the right represents 
a foot. Thus, if we wish to measure 3' 4}^", it would be the 



Q *4 



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^ 







24 HOW TO READ A DRAWING 

distance between the points A-B in Fig. 20, or 5' iiK" would be 
the distance between the points C and D in the same figure. 

Starting from the right-hand end of the scale and reading 
toward the left, w^e find that it is divided or graduated to suit 
yi' to the foot, — that is, the first half inch is divided in the 
same manner as the inch at the opposite end of the scale, and 
each half inch reading towards the left represents one foot. 
Thus, if we wish to measure 11' 4)^", it is the distance between 
the points E and F in Fig. 20, or 7' 6^^" would be the distance 
between the points G and H in this figure. 

In drawings where all the dimensions are given, a scale 
should never be used, and where all the dimensions are not 
given, the student should be sure that the drawing is made 
to scale before he uses the scale to determine definitely what 
the dimension is that is not given. When the scale to which 
a drawing has been made is not given, a good way to find out 
the scale of the drawing is to measure several of the dimensions 
which are given, or which are known, with a scale which will 
fit these sizes, or dimensions, and then it can be assumed 
that the balance of the drawing has been made to this same 
scale. 



CHAPTER VI 

Bolts, Nuts, Rivets, etc. 

Before taking up the question of ''How the different 
members and pieces of a structure are put in place," we will 
consider the materials with which they are fastened together, 
— namely, bolts, rivets, etc. 

Fig. 2 1 represents what is known as a square-head machine 
bolt with a square nut. The top view shows the shape and 
dimensions of the head, the elevation shows the diameter 
and length of the bolt, the bottom view shows the shape and 
dimensions of the nut. 

This is usually all the information that is given for nuts 
and bolts, for unless they are of a special make they usually 
conform to some well-known standard, such as Manufac- 
turer's Standard, Franklin Institute Standard, etc. The 
dimensions for all the standard makes of bolts, nuts, etc., can 
be found in hand-books published by manufacturers of this 
product; in case they are of a special make, all the different 
dimensions and views should be shown on the drawing which 
represents them. 

Fig. 2 2 represents what is known as a machine bolt with 
hexagon head and nut. Besides the head and nut being dif- 
ferent from the bolt shown in Fig. 21, the thread also is 
different, the thread shown in Fig. 21 being that which is 
known as a right-hand thread (which is more generally used), 
while the thread of the bolt shown in Fig. 22 is called a left- 
hand thread. 

To determine whether the thread of a bolt is a right-hand 
or left-hand thread, hold the bolt in a vertical position, then 
if it is a right-hand thread the threads will slope up toward 
the right hand, while left-hand threads slope up toward the 
left hand. 

Fig. 23 represents a slotted flat-head or countersunk-head 
bolt with a right-hand thread. The head of this bolt is similar 



HOW TO READ A DRAWING 

Fig. 21. Fig. 22. 



^ItNl 




Hvr^. 




^'^l^/4/>f£T£/r^4^////V£30Lr,^fl(^. ^/^^^^^£^r Af^<r^/^€ Asj,r', 5r//<^. 



Fig. 23. 



X 




j£- 



2z 



/• 



2^/^M£TE/^ /ijiT//e^i>^oi. r; 2 2 ^<t- 



BOLTS, NUTS, RIVETS, ETC. 



27 



Fig. 24. 



Ov<!5 



^*^ 
^ 



fL 



T^ 



Ju 



to the head of an ordinarv^ wood screw. The method of show- 
ing this thread is also different from that employed in Figs. 
2 1 and 2 2 ; but the method shown in Fig. 
23 being more easily drawn, it is more gen- 
erally used, and to those who are familiar 
with drawings it is as readily understood 
as any other method. 

Fig. 24 represents what is known as a 
button-head rivet. The heads of this style 
of rivets vary somewhat in different manu- 
facturing plants, but in shape are usually 
slightly less than a hemisphere. 

The sizes of all rivets and bolts are 
known by the diameter and length; the 
length is always the distance under the head 
to the extreme end of either rivets or bolts. 
Fig. 25 represents the ends of two plates 
which are connected together with rivets. 
It is only necessary^ that this joint be drawn, 
without showing the full length of the 
plates, as to show the full length requires 
both space and labor in making the drawing, which is not 

necessary, as we are at present 
Fig. 25. interested only in the joint. In 

^ i i I 1 I v^i I order that we ma}^ know that 

'. I "^5 ^^"^ ^' r the full length is not shown, 

the plates at the extreme right 
and left of the drawing are ter- 
minated by a wavy line, as 
though they were broken off. 
This wavy Hne indicates that 
the plate is not shown to its full 
length. If a straight line were 
used instead of a wavy line, it 
would of course indicate that 
the full length of the plate was shown. 

Full straight lines are used to show all but the broken ends 






VD 



^^-0 



4 



NnI 



T 



4;^ 



^7- 



t/z 



^ 



«J\ 



M 



NnI 



\.T- 



T 



28 HOW TO READ A DRAWING 

of these plates. The other end of the bottom plate, being 
invisible when looking at the top view, is indicated by the 
dotted line ; the dimension lines and dimensions are shown as 
was explained in a previous chapter. The side view shows 
how the plates lap over each other. The thickness of the 
plates are given and the rivets are shown to be button-head 
rivets. 

Fig. 26 represents the method of fastening two plates 
together by the use of bolts. 

Fig. 27 represents the method of fastening two plates 
together with countersunk rivets, — that is, countersunk on 
the top side into the surrounding material. This method is 



Fig. 26. 




>s 



Fig. 27. 



i3r 



ii 



4 



\-7- 



^J 



^J 



■t7 



^ 



Xn 



generally employed where it is desired to have a smooth sur- 
face, and where the rivet heads will not extend beyond the 
material which they fasten together. 

The student should now have a good idea of how the details 
of bolts and rivets are shown. When not otherwise indicated 
or noted on a drawing, all rivets are to be button-head rivets 
and are to be driven in the shop. When countersunk rivets 
are required, the open holes should be drilled out to suit the 
countersunk rivets which fit into them. 

''Shop rivet" is the name given to rivets which are to be 
driven in the shop. "Field rivet" is the name given to those 
which are to be driven during the erection of the structure, or 
in the field. 



BOLTS, NUTS, RIVETS, ETC. 



29 



"Open holes" are those which are to be left open in the 
shop, to suit either bolts or rivets which are to be used in the 
field. 

In order that each different style or shape of rivet may be 
readily understood, the following conventional signs which 
are used to describe rivets have been adopted by all the leading 
engineers and bridge and structural shops throughout the 
United States. 

Fig. 28. 
/^/ v£ T-s O^^/s^ /-/oi-S-s 




c>* 



^x 



C^-^ 



<y-x.i7 






•^ 

I 






S|5 



1 

IS 

I 



It is the usual practice to provide the open holes for rivets 
and bolts (where the holes are punched out or drilled out) 
Ke" larger than the diameter of the rivets and bolts which 
fit into them. 

The sizes of rivets, bolts, or open holes which are required 
are generally marked in some convenient place on the draw- 
ing, thus: 

Open holes ^y^^' dia. 
Rivets %" " 



30 



HOW TO READ A DRAWING 



All the main principles of structural drawing have now 
been explained, and all that is required now by the student 
is experience, in order to become proficient ; and in order to get 
experience in this line, I would suggest that the student secure 
from time to time drawings of various objects, whether of 
direct interest or not, and study them. Study the minor 



Fig. 29. 



g ) d) (^ d) ^ ^ d) 



ji':\ 



idx 



c.-^ r^ rz\ 



^y 



^zr 






t;^ \^i^ ^3^ 






•■I 

IS 






<< v3 "C^S 



I 



■5^^ 












I? 



I 

k 



k 



8 

k 



points, and if there are any of these points that you do not 
understand, or that you are not sure about, or that do not 
seem clear to you, go to some one who does understand them, 
learn all about them, master them; that is experience. 

The following chapters, however, are designed to explain 
the majority of these minor points and to make clear any that 
have not already been explained. 



CHAPTER VII 

Structural Details 

Fig. 30 represents the top, front, and end views of a 12'' 
I beam 31)^ pounds to the foot. On each end of this beam two 
angles 6" x 4" x Ke" x o' 7)^" long are shown, riveted in place, 
each pair of angles containing 5 rivets. 

On the extreme left end this beam is square; on the ex- 
treme right the end is shown coped to fit a 15'' I 42 pounds per 
foot, flush on top; i.e., the top flange of the 12" beam has been 
cut off so that it will fit into a 15" I beam running in the oppo- 
site direction, thus allowing both beams to be level with each 
other on top. The 15'' I beam is shown with light dotted lines 
merely, to indicate clearly why this beam has been coped. 
The top view of the I beam shows four open holes ; at the left 
end of the top view is shown the distance that these holes are 
apart, namely 2%". This dimension is known as the gauge 
of a beam, and is generally a standard dimension for all beams 
of the same size. One-half of the gauge (in this case i%") is 
measured from each side of the centre of the web of the beam. 
These holes are 5' o" apart (starting from either end of the 
beam in the opposite direction from the gauge), and these 
holes are also shown projected from the top view to the top 
flange, only, of the front view. This shows that there are no 
holes in the bottom flange of the beam. The connection an- 
gles are shown to be centrally located on the web of the beam ; 
this is known because the centres of the angles are half-way, 
or 6", from the top and bottom of the beam. The dimensions 
for the open holes and rivets are always given from the back 
of the angle to the centres of all holes. This is the correct way 
to give dimensions on angles, and the student should remember 
this important point. The end views are shown at both ends 
of the beam, and should be readily understood, without much 
comment. I might, however, mention that the top part of 
the end view, at the right-hand side of the front view, has a 

31 



HOW TO READ A DRAWING 




STRUCTURAL DETAILS 33 

series of light lines to show that the beam is coped. The title, 
"1-12" I 31)^ pounds Required. Marie Bi," signifies that one 
beam 12" deep, weighing t,i% pounds to the foot, is required 
to be finished exactly as per sketch. Bi is merely a mark 
which is to be written in the shop, somewhere on the beam 
(generally with white lead), so that the builder may be able 
to distinguish it from some other material he may have for 
erection which may resemble this beam somewhat but is not 
identically like it. 

It will also be noticed that this beam is shown as if broken 
in three places; this was done in order to show that length- 
wise the beam is not drawn to scale. As this beam is fifteen 
feet long, a full-length drawing would require very much more 
space, and this is quite needless, as every point is clearly shown 
that is necessary to properly understand what is required. 
This will be readily seen by the dimensions of the top view; 
if we were to measure with a scale any of the 5 feet dimensions, 
we would find that they do not measure 5 feet, and by observ- 
ing that the beam was broken between each of these dimensions, 
we would readily understand why they were not shown the 
full 5 feet. Another point that must be remembered: in all 
drawing where a dimension is given, even if it is very much 
out of scale, the dimension is to be followed instead of the dis- 
tance being measured with a scale, as a scale is to be used only 
on a well-made drawing where no dimensions are given. 

Fig. 31 represents what is known as a double I beam or 
I-beam girder. This consists in two beams joined together 
by cast-iron separators and bolts. The views represented are 
the top view, end view, front view, and view of separators. 
The top view and end view show how the separators are placed 
between the beams and how they are held in place by the 
bolts; the front view shows the distance between the separa- 
tors and how far they are placed from the ends of the beam. 
These are standard separators for this size of beam; a view of 
these separators, which shows their shape, is given above the 
end view. Complete details of separators can generally be 
found in hand-books issued by the steel manufacturers. 
3 



34 



HOW TO READ A DRAWING 



•fcrr. 



^:-^ 



1 

•l 
II 

II 
!i 

«Si— 

II 



II 

II 
It 



^ 



fk 



IT 
11 

!i 
I 



m 



ii 
II 
II 
II 

A 
I 

|l 
ll 
II 
II 

II 

: - HI -\ 

1 

II 

II 

!i_ 



^F^^F 



/^ 



^^=^^^r 



■^►7 W 



e 



i nr 



.<^/ 



/^ 






.<:i 












5^ 



§ 

^ 
I 



\ 

V 

.if 

I 







^ M- ^ ^1^ o 



STRUCTURAL DETAILS 35 

Fig. 32 represents what is known as a beam box girder. 
This is composed of two I beams connected together by means 
of a top and bottom plate, which are fastened to the top and 
bottom flanges of the beams by means of rivets. On the web 
of these beams there are riveted two sets of small angles, three 
to a set. In this sketch we have a number of the different 
elements which we will find in structural details. In the top 
view the heavy lines show the edges of the top plate and the 
dotted lines show the top flanges and webs of the two I beams. 
The dimensions show the distance centre to centre of the webs 
of the beams, also the gauge of the beams and the spacing of 
the rivets. The terms 13 spaces @ i'-o"=i3'-o'' simply 
means that the rivets are placed one foot apart and that there 
are 13 spaces. Sometimes on a drawing only a few of the 
rivets are actually shown, but the student or workman must be 
always guided by the dimensions when they are distinctly 
given. In the front view are shown the thickness of the top 
and bottom plate and depth of the beam, and on the left-hand 
side in the front view are seen three small angles w^hich are 
riveted to the w^eb of the front beam only. This is clearly 
understood by consulting the top view, which shows exactly 
on which beam these angles are riveted. On the right-hand 
side in the front view, in dotted lines, may be seen another 
group of small angles, which are the same as the angles on the 
left-hand side, except that they are riveted to the web of the 
far beam. In the bottom view the first two rivets on each 
end are shown to be countersunk on the bottom side. This 
bottom view also shows on which beam the small angles are 
riveted. The end view shows the general arrangement of the 
girder, and no further comment of this view should be necessary. 

The various parts throughout are named for one complete 
girder, and an arrow point is shown pointing to each piece des- 
ignating where the parts so named are located. The number 
to be furnished is two whole girders complete. 

Fig. 33 represents what is known as a plate and angle girder. 
This is a built-up section composed of one main centre plate 
(made in two pieces) known as a web plate ; this plate has 4 



36 



HOW TO READ A DRAWING 




*; 



Fig 




\ ^\y"\^\^i\9-5f>s.^3:2^3\ ^i"\ 3'^^^C^4t"-3'A7 1 ^%' 



/-/^ 










:3 7-o 



9- 



T^J:" M 



5^-5—5— -<)—(>--( ^-( 






L^ 



^i 



<)— ^ — Q 'I w^<rr/d?A'-/47A 



STRUCTURAL DETAILS 37 

main angles riveted to it, one at each side of the top and 
bottom, running horizontally; riveted to these angles, on the 
top and bottom of the girder, is a plate which is known as a 
flange plate ; on the end of the girder and at various distances 
from the end are angles riveted to the web plate and top and 
bottom angles. These angles are known as stiff ener angles; 
between these angles and the web plate are bars, of the same 
width as the legs of the angles, which are riveted to the web 
plate. These bars are known as filler bars and are generally 
called fillers. 

At the right-hand end of the drawing it will be noticed that 
the girder has been broken off, and a centre line marked "<^" 
is shown slightly to the left; this centre line is marked "sym- 
metrical about centre line." By this is meant that the girder 
is the same from centre line working toward the right as it is 
from the centre line working toward the left. This is a very 
convenient method of showing long objects which are identi- 
cally the same from both sides of the centre line to the ends, as 
it not only saves the labor of drawing the whole object, but 
also saves space on the drawing. 

All other views shown would be easily understood by the 
reader and require no comment, except that the view below 
the front view instead of being a bottom view is shown as a 
section. This section is taken as though the girder was cut on 
the line A A and the observer was looking down from above. 
This view is shown in this way so that full lines may be used 
to show distinctly the construction of the girder, instead of 
dotted lines which would of course be used if a regular bottom 
view were shown. Sometimes on a drawing this view is not* 
marked "section," where it is so clearly shown to be a sec- 
tional view that to those who are in any degree familiar with 
drawings no mistakes will occur. 

Fig. 34 represents what is known as a Z bar column. This 
is also a built-up section, composed of 4 Z bars riveted to a 
central plate known as a web plate. This is clearly shown by 
refering to the section marked A-A which also shows the 
construction of the base of the column. All the other views 



38 HOW TO READ A DRAWING 

are shown in such a manner that the reader should readily 
understand them. 

Fig. 35 represents what is known as a Tee brace. The top 
view of the tee is shown identically as the top view of an I 
beam would be shown, and the front view is shown exactly as 
the front view of an angle would be shown. But we know it 
is neither an I beam nor an angle, for three reasons : 

First, we must always study all the views of a drawing 
before we determine what the object represented looks like, 
for there are many objects that have one or more views which 
are identical, while the other views of these objects show 
in what particular respects they differ, and by doing this 
we easily see that it is not an I beam nor an angle. 

vSecond, the name of the material itself is sufficient to dis- 
tinguish it from any other section. 

Third, the end view clearly shows the shape of the object 
to be a tee. 

In this drawing there are several vital points that have not 
yet been explained. At the extreme right hand end of the 
tee, it will be noticed that there are dimension lines which 
form a triangle. On the horizontal dimension line is shown 
the dimension 12" and the vertical dimension line is marked 
<^yi' . This is called the level, and signifies that in order to 
bend this tee to the correct shape we must measure 12" in a 
horizontal direction from the point at which the tee starts to 
bend, and on a line at right angles to this line (that is, a ver- 
tical line) we must measure 9%", then, by drawing a line 
through this point to the point at which the angle starts to 
bend, we get the line or bevel or slope that the tee is to be 
bent. 

Riveted to the other end of the tee is shown a plate on 
which some of the holes are also laid off on a bevel ; this bevel 
is the same as the one already described, and, as the operation 
is clearly shown on the drawing, the student should not find 
any difficulty in following it. 

The next point to which I wish to call the student's atten- 
tion is that the drawing calls for two braces, — ^namel}^ one as 



Fi 



/-8" 







^£C T/O/^ 'A -A. 



Zll^ '^ '3 



^ps.cs>(5"=:^-o' ^6-S/:^s.(g)4' 







^- C^Z CfA^/V^ 



ni4- 










\^*^£^'/?. /y7A^< /. 



STRUCTURAL DETAILS 



39 




40 HOW TO READ A DRAWING 

per sketch and one the reverse of the sketch. This is some- 
times written, *'i Req'd, Right Hand, i Req'd, Left Hand, or 
I as per vSketch, i Opposite Hand." All these terms mean the 
same, — that is, that one piece is to be made exactly as it is 
shown in the drawing, and the other piece is to be made of 
the same size but just the reverse in shape. 

In order that the reader may clearly understand this 
method of showing right-handed and left-handed views of 
objects, the opposite hand or reverse of the object seen in 
Fig. 35 is shown in Fig. 36. The student will notice that Fig. 
35 is not simply turned around in Fig. 36, for if that were the 
case the plate on the end of the tee would be shown on the far 
side of the tee instead of on the near side, and there would be 
no necesssity for making these braces right- and left-hand. 

Now, the easiest way to find out what the reverse or oppo- 
site hand of an object looks like is to make, on a piece of paper 
that you can see through when you hold it before a bright 
light, a sketch of the object exactly as it is shown on the draw- 
ing, then by holding this paper before the light with the sketch 
side toward the light, you will see the reverse or the opposite 
hand of the object. However, if the paper or blue print on 
which the object was originally drawn is transparent, it is not 
necessary to redraw it ; simply hold it to the light in the manner 
described above. Try this, so you may see exactly how it 
works, before leaving this chapter. 

On the top view at the right-hand end of Fig. 35 and the 
left-hand end of Fig. 36, where the tee starts to bend, will be 
noticed a series of lines the same distance apart and as long as 
the width of the flange of the tee. These lines are very light 
where the tee starts to bend, but gradually increase in thick- 
ness as they near the end of the tee. These lines are called 
shade lines which represent a fiat surface and show that the 
tee is bent. As, however, the front view shows that the tee is 
bent and how it is bent, they are not absolutely necessary, 
but are placed on some drawings to show that an object is 
bent, when there is danger that the other views might not be 
taken into consideration in a hurried glance. Another rea- 



STRUCTURAL DETAILS 



41 




42 



HOW TO READ A DRAWING 



Fig. 37. 



son why they are not used, when a drawing is otherwise well 
made, is that they might interfere with the clearness of a 
practical drawing. 

Fig. 3 7 shows the method of presenting the shade lines of a 
curved surface or clyinder. The lines are light near the centre 
of the cylinder, with large spaces between them, but as they 
near either side the spaces gradually decrease 
in width and the lines become heavier. 

However, when there are other views 
shown which indicate the object as having a 
curved surface, it is not necessary to show 
by shade lines that the surface is curved, for, 
as explained before, these shade lines might 
interfere with the clearness of the drawing. 

The reader should by this time be able 
to understand any structural drawing, and in 
fact any drawing if he is familiar with the 
material which is represented by it, for with 
all classes of projection drawing objects are 
shown, by the same principles. There are, 
however, several points in what is known as 
Mechanical and Architectural Drawing that 
have as yet not been explained. The most important of these 
points will be taken up in the following chapters; but let the 
reader clearly understand that, while these various points may 
apply only to mechanical or architectural drawing, his knowl- 
edge of drawings is not complete without them, and failure 
on his part to become familiar with them will only result in 
his own loss. 




CHAPTER VIII 

Mechanical Drawings 

As mechanical drawings deal to a great extent with curved 
surfaces, our first consideration in this chapter will be the 
circle, as every curve is a portion of some circle. 

A circle is a single curved line every part of which is an 
equal distance from a point called the centre. 



Fig. 38. 



Fig. 39. 



Fig. 40. 




c://^^L ^ 



The distance around a circle is called the circumference of 
the circle. 

The distance across a circle, through the centre, is called 
the diameter. 

The radius of a circle is the distance from the centre of the 



Fig. 41. 



Fig. 42. 



^^c G^ C^^c^ I 



CA<o>^^f 



circle to its circumference, or one-half the diameter of a circle 
equals the radius. 

Any portion of the circumference of a circle is called an arc. 

The chord of a circle is a straight line joining the extremi- 
ties of an arc but which does not pass through the centre of 

43 



44 



HOW TO READ A DRAWING 



the circle ; if it passed through the centre of the circle, it would 

be called the diameter. 

For convenience in measuring any portion of a circle, the 

circumference is divided into 360 equal parts called degrees. 

Therefore, if a circle is divided into two equal parts, or in 

halves, each part contains 180 
degrees. If we divide the circle 
into four equal parts, or in 
quarters, each part contains 
90 degrees. If we divided it 
into eight equal parts, or in 
eighths, each part would con- 
tain 45 degrees, etc. 

In order to obtain very ac- 
curate dimensions, each degree 
is divided into 60 equal parts 
called minutes, and each min- 
ute is again divided into 60 

equal parts called seconds. Instead of using words to express 

degrees, minutes, and seconds, the following symbols are used: 

The symbol ° means degree or degrees 
The symbol ' means minute or minutes 
The symbol " means second or seconds 



1^0 




Fig. 44. 



Fig. 45. 



Fig. 46. 






Thus, if we wished to express fifty-six degrees, one minute 
and twenty-two seconds, it would be written 56° i' 22'^ 
These symbols are written above the line that the figures 
are on, and are so much smaller that they will not be mis- 
taken for figures. 



MECHANICAL DRAWINGS 



45 



An angle is formed when two straight Hnes meet. The 
Hnes are called the sides of the angle and the point where the 
lines meet is called the vertex of the angle. An angle which 
contains 90° is called a right angle. See Fig. 44. 

When an angle contains less than 90° it is called an acute 
angle. See Fig. 45. 

Fig. 47. 





Tl^/A^Cr/^^^. 



See 



An angle of more than 90° is called an obtuse angle. 
Fig. 46. 

A triangle is formed by connecting the extremities of the 
sides of an angle with another straight line. See Fig. 47. 

A protractor is an instrument used for measuring degrees 
and proportions of degrees. See Fig. 48. 

Fig. 48. 




For convenience, protractors are numbered from 0° to 
180° in both directions, so that the number of degrees or por- 
tions of degrees may be easily found by starting from either 
the right-hand or left-hand side of the diameter of any circle. 
In using a protractor it must be placed so that the line form- 
ing one side of the angle will be in line with the points 0-0 
on the protractor and the vertex of the angle must be at the 
point marked C. Thus, to lay off 35 degrees (see Fig. 48), 



46 



HOW TO READ A DRAWING 



start at the line marked o at the right-hand side of the pro- 
tractor, then from the point where the divisions show 35 
degrees draw a hne to the vertex, marked C; this will give you 
an angle of 35 degrees. 

On a drawing the different kinds of material used in the 
construction of an object may be indicated in the sections by 
various methods of shading. Some of these methods are 
shown in Fig. 49, and the}^ have been universally adopted by 
the leading engineers of this country as standard. However, 
each kind of material presented on a drawing should be clearly 
marked with the name of the material out of which it is made. 

Steel is indicated by drawing two light lines close together, 
then leaving a space equal to the two light lines, then repeat- 
ing with two more light lines, etc. 



Fig. 49. 







CCA/C^£T£ 



Wrought iron is indicated by alternate light lines and heavy 
lines at equal distances apart. 

Cast iron is represented by a scries of parallel light lines 
an equal distance apart. 

Brass is indicated by alternate light full lines and light 
dotted lines. 

Babbit metal is indicated by light lines which cross each other. 

Wood is sectioned by a series of irregular curved and radiat- 
ing lines, and resembles the cross section of a tree. 

Concrete is indicated by dots and small dashes. 

There are many other materials for which standard 
methods of sectioning have been adopted, but, as a general 
rule, when a material is indicated on a drawing, the name of 
that material is noted somewhere on the drawing. 



CHAPTER IX 

Gearing; Finishing; Storage Tank; and Valve 

Fig. 50 represents what is known as a gear wheel. In 
this drawing is shown the method of projecting from one view 
to another; this method has been explained in detail in pre- 
vious chapters. 

There are several terms used in connection with gearing 
that the student should become familiar with; these terms or 
names, it will be noticed, are marked on the drawing, the 
meaning of which should be self evident. 

A complete treatise on gearing may be secured at very 
little expense by applying to any well-known manufacturers 
of gear-cutting machinery, who issue catalogues and booklets 
on this subject. The Brown & Sharp Manufacturing Company, 
of Providence, Rhode Island, publish a book called "A Prac- 
tical Treatise on Gearing," which is, in my estimation, one 
of the best books on this subject that is published. 

There is a point in cormection with drawings which has 
not been explained before and to which I wish to call the 
reader's attention, and that is in reference to the finishing of 
material, or the machine work. When it is necessary to perform 
any finishing work on material, such as boring, turning, drill- 
ing, planing, threading, etc., or doing any work by the use of 
machinery, the operations performed are generally known as 
machine work. Before any machine work has been performed 
on a casting, the casting is known to be in the rough. When it is 
required to perform machine work on a certain portion of the 
casting, such as facing the ends of the hub of a gear wheel 
(see Fig. 50), the casting in the rough is made a trifle larger 
at this point than the dimensions called for on the drawing, 
so that before this casting is machined there shall be a little 
surplus material on the casting which is cut off by the machine. 
By this method, the casting can be finished to a true, smooth 
surface, the machinist adhering to the dimensions shown on 

47 



48 



HOW TO READ A DRAWING 




GEARING, FINISHING, STORAGE TANK, AND VALVE 49 

the drawing. This surplus material is usually called stock 
or finish. 

When an object is to be machined or finished, any of the 
following words are used to denote the machine work: bored, 
planed, milled, faced, etc. There is another mark or symbol, 
however, that is a substitute for any of these words, — that 
is, the letter "f," which denotes, wherever it occurs on a 
drawing, that that part of the material is to be finished or 
machined. 

Cored holes, or cored openings, are made in the process of 
moulding castings; they are considered rough holes, and are 
usually made from /s" to V" larger than the bolts, etc., which 
fi^t into them. Cored holes are generally used when it is not 
necessary to make a water-tight joint, and where it is practical 
to core the holes in the process of moulding. 

Fig. 5 1 represents what is known as a cast-iron storage and 
settling tank. This tank is used for the double purpose of 
storing a liquid and at the same time allowing any sediment 
which may be in it to settle to the bottom of the tank. 

The construction of the tank is very simple, and, by apply- 
ing the principles described in the previous chapters, should be 
readily tmderstood; but, as this subject affords an excellent 
opportunity to review some of the minor points which we 
have passed over in the last chapter or so, we will go into it in 
detail. The tank in its erected form is shown by Fig. 51, 
which also includes a bill of material. This bill of material 
is simply a list of all the material required to build the tank, 
and the details of all the parts, that are not of a standard 
make, are clearly shown by Fig. 52. 

Fig. 51 shows the tank to have four legs, marked "D," at 
the bottom of the tank. These four legs are connected to 
the bottom head, marked "B." In each of these legs are two 
cored holes for %" diameter machine bolts, which are shown in 
the bill of material as being \Y^' long. As these bolts are of 
standard make and can be ordered or secured from any dealer 
who handles this class of material, no detail drawing is shown 
or required, as is the case with all the bolts which are required 
4 



50 



HOW TO READ A DRAWING 



for the construction of this tank. As will be noticed by refer- 
ring to the detail shown by Fig. 52, the top of these legs and 
the bottom of the lugs, which are on the bottom head and 
onto which the legs are to be connected, have finished surfaces, 
as is designated by the symbol "f." These surfaces are ma- 
chined or finished so that the heater will rest squarely upon 



Fig. 51. 




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its legs. The holes in the lugs of the bottom head and in the 
top of the legs are cored, because in this case it is not neces- 
sary that this joint should be water-tight and it is usually 
cheaper to core holes than to drill them. In the centre of 
the bottom head will be noticed a hole which is to be tapped 
for standard W. I. pipe. Into this hole is screwed a standard 
y" brass stopcock, marked "T," which like the bolts may be 
purchased from any dealer who handles this class of material, 








A c. I. eoTTO/rr hsao /yiK:>. B. 








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GEARING, FINISHING, STORAGE TANK, AND VALVE 51 

and therefore requires no detail drawing. The purpose of 
this stopcock is to drain the tank when the occasion requires it. 

Connected to the bottom head " B " is a cyHndrical shell 
marked "C." This shell is i8" inside diameter and 3' 6)^" in 
length. At the top and bottom of the shell are flanges which 
are 2' o" outside diameter. These flanges have finished sur- 
faces and edges, and 16 holes are drilled in each flange for bolts 
%''' diameter. When this tank is being erected, between these 
flanges and the flanges of the top and bottom heads are placed 
white lead and what is known as cotton torch-wick; this is 
done to make sure that the joints shall be water-tight. Near 
the bottom of this shell is shown a 12" opening, which is cov- 
ered by a circular cleaning door, marked "E." This clean- 
ing door is held in place by 12 stud bolts (w^hich are bolts 
which have no heads, both ends being threaded, and these 
bolts are screwed into tapped holes which are provided for 
them) ; the face of this opening and the flange of the door are 
machined, and white lead and cotton wick are used to make 
this joint water-tight. There are two other openings in this 
shell, — one, near the bottom, for a \y" pipe outlet, through 
which the liquid flows from the tank, and the other, on the 
same side of the shell near the top, through which the arm 
that operates the float passes. 

This particular point may be more thoroughly under- 
stood by studying the section at the top of Fig. 52. In the 
inside of this tank after it is erected is a copper float, marked 
**P," which on account of its buoyancy always floats on the 
liquid in the tank, and this float, by moving up or down as 
the tank either fills or empties, operates (shuts off or opens) 
the balance valve, marked "L," which is shown at the top of 
the tank on Fig. 51. This balance valve is connected to a 
wrought-iron lever, marked "M," by an operating rod "Q," 
to which at each end is attached a forging, " O. " This wrought- 
iron lever, "M," is attached to a bravSS arm, marked "K," 
and on the end of the arm "K" is connected the copper float 
"P." In order that this arm "K" may pass through the 
side of the tank without causing the tank to leak, a stuffing- 



52 HOW TO READ A DRAWING 

box, marked "J," and a gland, marked "H," are used. The 
stuffing-box fits into the opening in the side of the shell and 
is held in place by a stud bolt at the right and left side of the 
stuffing-box. Into the stuffing-box the gland "H" fits, and 
this gland is held in place by a stud bolt at the top and bot- 
tom of the gland. These stud bolts are longer than the stud 
bolts which hold the stuffing-box in place, and they are tapped 
into the shell and go through the stuffing-box and gland. 
This construction allows the gland to move in and out, as the 
nuts of the stud bolts are tightened or loosened. This is done 
for the reason that at the end of the gland, between the gland 
and the stuffing-box, packing is placed, .and, as this packing 
wears out, the nuts on these stud bolts may be tightened and 
will press the packing closer to the brass arm "K," or they may 
be loosened and the gland removed and new packing put into 
place. 

The balance of these details should be readily understood, 
as all that remains to be explained is, that at the top of the 
heater the top head is tapped to receive a i)^'' inlet nipple; 
this is screwed into a standard C. I. elbow, which in turn is 
connected to a i^" W. I. pipe that leads to a standard balance 
valve. All these pipe fittings being standard, no detail draw- 
ing is required. On the lever of the balance valve **L," and 
the W. I. lever "M," are placed counterweights, **F," which 
are used simply to adjust the operation of the valve. 

As all the parts of this tank that are not standard are 
detailed, the student should carefully go over each detail and 
see exactly where each part fits in the construction of this 
tank, as there may be very many important things that are not 
quite clear at the first glance, and in this subject the student 
will find many points in mechanical drawing that he will meet 
with in the course of his career. Therefore, again I say, do not 
pass this chapter without clearly understanding all that it 
contains, for to miss any of the small particulars set forth here 
might be a stumbling-block at some future time. Think this 
all out for yourself, and any other points that you may come 
across, and, if you do not fully understand it all, go over it 



GEARING, FINISHING, STORAGE TANK, AND VALVE 53 

again; if necessary, start at the beginning of the book; it is 
all explained, and has been fully understood by others and can 
be by you if you have a little patience and do not hurry through 
it or give it a careless glance, and, if you succeed, and under- 
stand it all, you may be positively sure that you can master 
any well-made drawing that you will come in contact with. 

Fig. 52 A represents what is known as a 6" globe valve. 
This style of valve is generally used on steam lines, and, as it 
is so completely shown, no detailed explanation is necessary. 
The student, however, should not pass hurriedly over this 
drawing, but should study out, and thoroughly understand, 
all that it contains. 

In reference to the next chapter, entitled Architectural 
Drawing, do not be misled by the name, for, while you may 
think that you will have no need for the information contained 
therein, go through it to the end and your views will change; 
and after you have mastered it, as you have mastered these 
other branches, you would not part with your information at 
any price. 



CHAPTER X 

Architectural Drawing 

In this treatise it is my intention simply to show the reader 
the general manner in which structures, buildings, etc., are 
represented by projection drawing. Usually there accom- 
pany every set of drawings of a building or structure what 
are known as specifications. These specifications are written 
descriptions of the structure; they also specify the name and 
quality of all the materials which are to be used throughout 
the structure, and they are intended to supply any information 
which could not be conveniently given on the drawing. 

The first illustration in this chapter, Fig. 53, represents 
the shape and size of a plot of ground and the plan view of the 
foundation of an ordinary dwelling-house. This plan is shown 
as though it was a section taken immediately below the first- 
floor line or directly above the level of the ground. In this 
view it can readily be seen how the house will be situated on 
the plot of ground, or lot, as the size and shape of the founda- 
tion walls and various other dimensions are given. 

Fig. 54 represents the plan view of the first-floor, and is 
shown as though it was a section taken immediately above 
the first-floor line. In this view are indicated the size of the 
various rooms and hall, location of windows, doors, and chim- 
neys, and the thickness of walls, width of stairs, and other 
important dimensions are given. 

Fig. 55 is a plan view of the second floor, which is shown as 
though it were a section taken immediately above the second- 
floor line. This view, like the plan view of the flrst floor, 
shows the shape and location of the rooms, halls, walls, stairs, 
etc., as well as the most important dimensions. 

Fig. 56 shows the plan of the attic or third floor. This 
view is taken as though it were a section immediately above 
the third-floor line, and, like the first- and second-floor plans, 
all the necessary dimensions are given. 

5i 



.ARCHITECTURAL DRAWING 



55 



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HOW TO READ A DRAWING 




ARCHITECTURAL DRAWING 



57 




58 



HOW TO READ A DRAWING 



Fig. 56. 






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ARCHITECTURAL DRAWING 59 

Fig. 57 represents the front view, or front elevation, of 
the house, showing the style of porch, steps, doors, windows, 
roof, and the various ornamentations of the front of the house. 

Fig. 58 presents the rear view, or rear elevation, of 
the house, and, as in the front view, or front elevation, all the 
prominent parts, such as porch, doors, windows, chimneys, 
rain conductors, roof, etc., are shown. 

Fig. 59 represents a longitudinal section of the house, — 
that is, a section taken through the lines A-A on the first- 
floor plan. In this view is shown all the visible interior of the 
house as it would look if the house were to be cut along the 
line A-A and the part nearest to you were removed. All the 
important dimensions which were not given in the other 
views are given in this view, such as the depth of the founda- 
tion, height of stories, size of joists, etc. 

By studying these drawings the reader should be able 
thoroughly to understand the general requirements of the 
building. In ordinary buildings of this kind it is very seldom 
necessary to give any details other than those that are shown 
for windows, doors, fireplaces, porch columns, etc., as the 
specifications generally state the quality of the material which 
is to be used, and the manufacturers of this material issue 
illustrated catalogues, or have show-rooms in which can be 
seen the various styles of doors, windows, fireplaces, chande- 
liers, stairways, etc., from which the architect, contractor, or 
owner generally selects the designs of these objects according 
to his own taste. However, if it is desired to have some par- 
ticular object, such as a china-closet, etc., that is not standard, 
the architect generally shows a detail of it, which when given 
may be readily understood in accordance with the principles 
set forth in the preceding chapters. 

In designing large buildings, especially where steel con- 
struction is used, the architect provides what is known as 
framing plans, which give the size and general dimensions of 
the structural material used in the construction of the build- 
ing. These framing plans are simply the plan views showing 
the material which is used, at a point immediately below 
the floor hne. 



60 



HOW TO READ A DRAWING 

Fig. 57. 



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Front view or front elevation, residence for Mr, H. Deeds. 



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[DENCE FOR Mr. H. DEEDS. 



ARCHITECTURAL DRAWTNG 

Fig. 58. 



61 




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HOW TO READ A DRAWING 









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64 HOW TO READ A DRAWING 

Fig. 60 represents the plan view of the structural 
framing of the building immediately below the floor line, and 
the sections show how the different members are connected 
together. The reader should have no trouble in following this 
drawing, for with the addition of a few intermediate dimen- 
sions it would be almost a complete detail drawing. The only 
features that have not already been explained are the numbers 
which are given to the different members which are shown on 
this drawing. These numbers should be marked on the com- 
pleted material when it is made in the shop, so that the erector 
will have no trouble in putting the material in place during 
erection, exactly as it is called for on this drawing. 

It will be noticed that the sections which are seen on this 
drawing are not shown with the usual section lines, but all the 
lines are solid. This method is very often used in sectioning, and 
is as readily understood as any other. This drawing is a little 
unusual, how^ever, as a much shorter method of showing exactly 
the same thing can be employed, and, as the whole purpose of 
drawings of this kind is to show the object or objects in as brief 
a manner as is consistent with clearness, the method shown in 
Fig. 61 is usually employed, and is to those who are familiar 
with it as clear and distinct as the drawing shown in Fig. 60. 

Fig. 61 is what is known as a single-line drawing, and shows 
exactly the same material as is seen in Fig. 60, except the 
connections angles, which are not shown in the plan view, but 
which are shown in the sections of both drawings exactly the 
same. The only difference in these drawings is that Fig. 60 
gives a complete top view, while in Fig. 61 only a single line 
is shown; but, as all the members are clearly named and the 
sizes and weights of the material are also given, it is not neces- 
sary to show a complete view in a drawing. 

All the different classes of drawings relating to construc- 
tion work have now been explained, and it is up to the reader 
to make good, and this can be accomplished by a little study. 
Go over each chapter and each illustration and think it all out, 
and you will find that it is very easy to master, and, if you 
master it, you will as you journey through life find that it will 
be one of the greatest assets which you possess. 



NOV 21 1912 



